全文获取类型
收费全文 | 502篇 |
免费 | 2篇 |
国内免费 | 2篇 |
专业分类
化学工业 | 9篇 |
金属工艺 | 12篇 |
机械仪表 | 6篇 |
建筑科学 | 7篇 |
矿业工程 | 1篇 |
能源动力 | 2篇 |
轻工业 | 9篇 |
水利工程 | 2篇 |
无线电 | 7篇 |
一般工业技术 | 13篇 |
冶金工业 | 433篇 |
自动化技术 | 5篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2018年 | 3篇 |
2017年 | 1篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 3篇 |
2011年 | 9篇 |
2010年 | 13篇 |
2009年 | 1篇 |
2008年 | 3篇 |
2007年 | 1篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 2篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1999年 | 15篇 |
1998年 | 101篇 |
1997年 | 76篇 |
1996年 | 44篇 |
1995年 | 34篇 |
1994年 | 29篇 |
1993年 | 27篇 |
1992年 | 4篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 6篇 |
1979年 | 1篇 |
1977年 | 16篇 |
1976年 | 27篇 |
1975年 | 2篇 |
1963年 | 1篇 |
排序方式: 共有506条查询结果,搜索用时 0 毫秒
501.
502.
503.
MY Zhou H Klitgaard B Saltin RR Roy VR Edgerton PD Gollnick 《Canadian Metallurgical Quarterly》1995,78(5):1740-1744
The influence of microgravity on the myosin phenotype of skeletal muscle fibers in the vastus lateralis of eight crew members was studied before and after 5-day (n = 3) and 11-day (n = 5) spaceflights (space shuttle flights: STS-32, -33 and -34). Single-fiber electrophoresis analyses showed that the proportion of fibers expressing only slow (type I) myosin heavy chain (MHC) in the vastus lateralis was significantly lower after than before 11 days of spaceflight. Although the family of type II MHC isoforms was elevated post- compared with preflight, the distribution among the isoforms of type II MHC was not statistically different. Based on monoclonal and polyclonal antibodies specific for three adult MHC isoforms and single-fiber electrophoresis, approximately 3% of the fibers analyzed coexpressed all three adult MHC isoforms. The results from immunohistochemical staining with two different sets of antibodies indicate a reduction in the percentage of fibers expressing type I MHC as a result of spaceflight. The mean difference, however, was significant only when the fibers were categorized simply as type I or II. These changes appeared to be highly individualized among the astronauts. These results suggest that a rapid change in MHC isoform expression can occur in some muscle fibers after a relatively brief exposure to spaceflight. 相似文献
504.
VR Ermolaev GM Shub EP Kusina GL Polianski? VI Sobolev 《Canadian Metallurgical Quarterly》1976,10(3):53-58
Recovery of spatial resolving capacity (acuity) of central vision after temporary blindness induced by prolonged (1.5, 3, 6 min) light adaptation to a sun or incandescence lamp (20, 40, 80 thous. lux) illuminated white screen was studied. The recovery time increased exponentially with an increase in energy light stimulation (product of brightness of the deadapting source by the time of action). A general formula describing the relationship between the time of recovery of acuity and brightness of the test table and energy of light stimulus was derived. 相似文献
505.
There are over 500 water supply reservoirs in England and Wales, a total water surface of 20000 hectares, much of which has been flooded this century. Waterfowl, amphibious and aquatic wildlife have all benefited from this change, especially important after so much wetland has been drained and ploughed to increase agricultural production. Modern reservoirs include landscape and conservation in their planning, construction and operation, often leading to their notification as Sites of Special Scientific Interest soon after their construction. Examples in the Anglian Water and Thames Water regions are discussed to demonstrate their value to wildlife as well as fulfilling their prime function for water supply. Pitsford Water (Northamptonshire), Rutland Water (Leicestershire), Staines Reservoirs (Surrey), and Walthamstow Reservoirs (Greater London) show varying levels of conservation planning. Protection from recreational activity is shown to be an essential part of management at these sites. 相似文献
506.
J Kobayashi C Mavroudis SE Crawford VR Zales CL Backer 《Canadian Metallurgical Quarterly》1993,12(4):659-664
Considerable progress has been made in survival rates of heart transplant recipients; however, infections continue to be a major cause of death after transplantation. Although infection itself appears to cause immunologic suppression in some nontransplantation studies, the lack of an infection-transplant animal model has limited further investigation of this observation. We evaluated the utility of a heterotopic rat infection heart-transplant model by studying the effect of infection and limited administration of two immunosuppressive agents, cyclosporine and FK506, on allograft rejection and survival. Lewis rats received ACI heart allografts, and intraperitoneal infection was induced by cecal ligation. Infection was confirmed by blood and ascitic fluid cultures. Results showed that graft survival was slightly, but significantly, higher (p < 0.05) in group II (transplantation with infection) when compared to the control group I (transplantation only). Histologic rejection scores were less (p < 0.05) in group II 6 days after transplantation. The second phase of the study compared the effect of infection after transplantation in rats given a 1-week course of cyclosporine or FK506, which were discontinued after the induction of infection. Although the cyclosporine group had prolonged survival when compared to the FK506 group (p < 0.05), the respective infection groups receiving immunosuppression revealed no significant difference in allograft survival or histologic rejection scores when compared to the control groups. In this preliminary study, infection without immunosuppression resulted in a slight, but statistically significant, increase in allograft survival and reduced acute cellular rejection. In those groups receiving immunosuppressive agents, no additive immunosuppressive effect was attributable to bacterial infection.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献